The correct answer is option A, that is, building more gasoline powered cars.
In the present global warming issue, the prime cause is the human exploitation of the greenhouse effect. The greenhouse effect leads to warming when the atmosphere holds the heat radiating from Earth from going back to space, that is, certain gases present in the atmosphere blocks the heat from leaving.
However, the increase in the concentrations of carbon dioxide and other greenhouse gases in the atmosphere have resulted in the increase of the greenhouse effect leading to global warming. These gases have increased since the start of the industrial period, and almost all this is primarily due to human actions.
Thus, building more gasoline powered cars would result in more increase of greenhouse gases and eventually resulting in more greenhouse effect.